The Assessment of Hazard in the Manual Handling of Explosives
Initiator Devices

R. K. Wharton*

Health and Safety Laboratory, Harpur Hill, Buxton, Derbyshire, SK17 9JN (United Kingdom)

A. W. Train

Health and Safety Executive, Hazardous Installations Directorate, Merton House, Stanley Precinct, Bootle,
Merseyside, L20 3DL (United Kingdom)

P. F. Nolan and S. C. Campbell

Chemical Engineering Research Centre, South Bank University, 103 Borough Road, London, SE1 0AA (United Kingdom)

Summary

In this paper we review recent research undertaken with the aim of

developing a compression test apparatus that simulates the application
of mechanical forces to which initiator devices may be typically
subjected during handling. This resulted in the development of two
different apparatuses, one supplied pressure by means of a weighted
beam and the other by using a pneumatic piston. The latter unit has
also been used to study the response of initiator devices to impact.
Additionally, we discuss some of the key information that would be
required in order to develop a safety-in-handling hazard index.

1. Introduction

A recent examination

(1)

of reported accidents in the UK

explosives industry over the period 1976–1992 indicated that
123 had involved initiator devices (initiators) and that 13 of
these had involved the device being handled by an employee.
Although it was possible to provide an explanation for 11 of
the incidents, the causes of the remaining two were not found
and they were ascribed to the excessive application of
handling forces by the process workers. Since 4 of the 11
cases had already been attributed to the same cause, this
suggested that roughly 50% of the reported occurrences with
initiating devices resulted from mis-handling.

Since there was no test method available to determine the

sensitiveness of initiators to the magnitudes and rates of
application of forces that may be exerted during manual
manipulation, the Health and Safety Executive placed a
research contract with South Bank University to develop a
simulation test method that could be used for screening
purposes.

The first stage of the work involved the development of an

apparatus for measuring the forces exerted in the manual
handling of small cylindrical objects (dummy initiators).
This apparatus was commissioned using laboratory staff
and then used for on-site measurements in the explosives
industry. The results obtained

(2)

indicated that both the

magnitude and rate of application of the handling forces
were dependent on the length and diameter of the cylindrical
objects being handled.

The study provided a definition of the parameters that

needed to be replicated in apparatuses constructed in the
second, laboratory stimulation stage of the project. Two units
were built with an initial view of reproducing typical manual
handling forces

(2)

; one used a pivoted beam

(3–5)

and the

second employed a pneumatic piston

(6)

. Extensive test pro-

grammes with each apparatus produced no ignitions for 13
different types of initiators: 3 percussion caps, an electric
(conducting composition) cap, 4 stab detonators, a flash
sensitive detonator, 2 electric detonators and 2 stab type
initiators.

The units were then used in an attempt to determine the

force that was required to initiate each device i.e. by applying
progressively greater forces than those encountered in
normal manual handling. Even though the manual handling
thresholds were greatly exceeded it was still not possible to
obtain initiation of any of the devices.

These results indicate that the recorded industrial ignitions

may not have resulted purely from compressive forces.
Previous laboratory work

(7)

has shown that manufacturing

defects such as bowed pressure discs, voids in the composi-
tion or composition trapped between the pressure disc and the
crimped end of the detonator case could exert an influence on
the likelihood of initiation. Furthermore, Ye et al.

(8)

have

highlighted that a number of operator-related and environ-
mental factors could also be important.

*Corresponding author; e-mail: [e-mail]

#

WILEY-VCH Verlag GmbH, D-69469 Weinheim, 2001

0721-3115/01/0410–0174 $17.50þ:50=0

174

Propellants, Explosives, Pyrotechnics 26, 174–179 (2001)

In the present paper we extend our previous work to

examine other results relating to safety in handling (those
derived from impact tests) and discuss the type of data that
would be required to form the basis of a hazard index to
reflect this aspect of industrial explosives processing.

2. Impact Test Methods

One factor to be considered when undertaking an assess-

ment of safety in the handling of initiators is their response to
knocks or to being dropped on to a hard surface. Nabiullah
and co-workers

(9)

investigated the reaction to impact of the

type of instantaneous electric bridgewire detonators used in
mines. The study incorporated a review of earlier work,
including that by Kimura et al.

(10)

and Beaker

(11)

, and

concluded that these devices are susceptible to initiation if
impacted with sufficient force (or if heated enough). Ignition
occurred with impact energies in the range 7–10 J and the
detonators were found to be more sensitive to impact when
mounted horizontally, particularly for impacts on sections
containing the fusehead or delay element.

2.1 Pneumatic Piston Test

Although designed initially as a compression test appara-

tus, the pneumatic piston unit

(6)

was also used to examine the

response of a range of initiators to dynamic (impact) forces.
Whereas manual compression forces are applied relatively
slowly and are to an extent distributed throughout an object,
impact forces are applied very rapidly and produce complex
stress waves within the impacted object. Details of the testing

sequence employed have been published elsewhere

(6)

and the

experiments yielded information on the highest piston gas
pressure below which no ignitions occurred. The minimum
impact stimulus was defined as the next highest pressure
above this value at which an ignition resulted

(1)

.

The energy imparted to initiators during pneumatic piston

impact tests can be estimated from either the kinetic energy
of the plunger or the work done by the compressed gas on
expansion. Since the latter involves a number of gross
assumptions (e.g. ideal gas behaviour, isothermal expansion,
no friction) the simple kinetic energy method will yield the
more accurate results, Table 1. Individual energies evaluated
in this way are roughly a factor of 3–5 less than those derived
from considerations of the expansion of the compressed gas
in the pneumatic cylinder.

The results obtained in the impact testing of a range of

initiators are summarized in Table 2.

2.2 Drop Ball Impact Test

Drop weight impact tests have been widely used for a

number of years to assess the sensitiveness of explosives, and
a selection of the most common units features in the Series 3
tests of the United Nations scheme for assessing safety in
transport

(12)

.

A similar test has also been employed to assess the

response of mechanically operated initiators to impact
stimuli. The method involves dropping a metal ball of
known mass from a range of heights on to a needle resting
on top of the initiator. The purpose of the test is to determine
the drop height that results in initiation but because of energy

Table 1. Range of Theoretical Impact Energies that can be Generated by the Pneumatic Piston Apparatus

Pneumatic cylinder pressure (MPa)

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Piston velocity

a

(m s

ÿ

1

)

0.77

0.96

1.13

1.28

1.41

1.52

1.61

1.69

1.74

Impact energy

b

(m J)

20.6

32.0

44.4

57.1

69.5

81.0

91.2

99.7

106

a

Derived from calibration graph of piston velocity against cylinder pressure obtained from measurements with a linear voltage
displacement transducer

b

Calculated as the kinetic energy of the piston

Table 2. Impact Test Results Obtained Using the Pneumatic Piston Apparatus

Initiator type

Pneumatic cylinder

pressure (MPa)

Minimum piston velocity

for ignition (m s

ÿ

1

)

Minimum impact energy

for ignition (m J)

Boxer cap

0.30

1.13

44.4

Berdan cap, type 1

0.15

0.86

26.1

Berdan cap, type 2

0.15

0.86

26.1

Stab detonator (two discs),

a

type 1

0.15

0.86

26.1

Stab detonator (two discs), type 2:
Red disc impacted

0.15

0.86

26.1

Blue disc impacted

0.80

1.69

99.7

Stab detonator (one disc), type 1

0.20

0.96

32.0

Stab detonator (one disc), type 2

0.30

1.13

44.4

Flash sensitive detonator

0.85

1.72

103.2

Stab type igniter (two discs)

b

, type 1

0.35

1.20

50.8

Stab type igniter (two discs), type 2:
Small disc impacted

0.40

1.28

57.1

Large disc impacted

0.35

1.20

50.8

a

Red disc impacted, yellow disc gave no ignition

b

Brass disc impacted

Propellants, Explosives, Pyrotechnics 26, 174–179 (2001)

Hazard in the Manual Handling of Explosives Initiator Devices

175

losses on recoil of the ball it is difficult to estimate the
minimum ignition energy and the method has become a
‘go’–‘no go’ means of monitoring consistent sensitivity in
production.

More recently, these deficiencies have been examined by

Woods et al.

(13)

and a modified unit has been produced with a

more consistent performance and with instrumentation to
enable evaluation of the magnitude and rate of application of
forces by the dropped ball to the firing pin.

It is possible to calculate the ‘all-fire’ impact (i.e. poten-

tial) energies for certain initiators from knowledge of the ball
masses and drop heights. Table 3 summarizes the results and
also presents data for the ball velocity at impact evaluated
from the equation for terminal velocity.

3. Discussion

From our previous study of the ergonomic aspects of

handling small cylindrical objects

(2)

it is possible to estimate

the maximum compression forces and application rates that
could be applied by a typical operator to the 13 ini-
tiator devices examined in the compression studies

(5,6)

.

Table 4 lists the values in units which can be directly
compared to the mean forces and mean peak force applica-
tion rates for both the pivoted beam and pneumatic piston
apparatus, Table 5.

With estimated handling forces ranging from 37.2–55.9 N

and 23.5–33.3 N for male and female workers, respectively,
it is apparent that the test units are both easily capable of
reproducing those compression forces likely to be encoun-
tered during manual handling. Similarly, the mean peak force
application rates in Table 5 are significantly greater than the
estimated handling values in Table 4.

When examined against this background, the fact that no

ignitions were obtained in the test programmes involving
both test methods suggests that factors other than simple
compression may have been involved in the reported indus-
trial incidents. Other considerations such as the extensive-
ness of the test programme when applied to low probability
events, the general robustness of electrically initiated
detonators (which are designed to be electrically and not
mechanically initiated), and the rapid rate of force applica-
tion generally used to initiate stab sensitive initiators, could
also have exerted an effect.

Although not part of the originally planned manual hand-

ling programme, additional information obtained from the
impact test work has provided a means of assessing certain
hazards associated with the accidental functioning of initia-
tors. Thus the work has also provided data on peak sound
pressure levels, the extent of fragment production on func-
tioning and the ability of some, but not all, detonators to be
functioned by an impact at either end

(1)

.

Table 3. Calculated Drop Ball Impact Energies

Initiator type

Diameter of

striker tip (mm)

Mass

of ball (g)

All fire

height (mm)

No fire

height (mm)

All fire

energy (m J)

No fire

energy (m J)

Ball impact velocity,

all fire (m s

ÿ

1

)

Boxer cap

1.52

114

310

75

347

84

2.46

Berdan cap, type 1

2.9

57

203

–

114

–

1.99

Berdan cap, type 2

1.98

227

178

51

396

114

1.87

Stab detonator (1 disc)

0.08–0.20

28

254

–

70

–

2.23

Stab type initiator

(2 discs), type 1

0.08–0.20

28

152

–

42

–

1.73

Table 4. Maximum Compression Forces and Application Rates that could be Applied to a Range of Initiators, Estimated from Ergonomic
Study

(2)

Initiator type

Diameter

(mm)

Length

(mm)

Estimated maximum

handling forces (N)

Estimated maximum

application rates (N=ms)

Male

Female

Male

Female

Berdan cap, type 1

4.54

2.23

37.2

23.5

0.088

0.059

Boxer cap

4.42

3.06

37.2

23.5

0.088

0.059

Berdan cap, type 2

5.49

2.91

45.1

27.4

0.098

0.069

Electric cap, conducting

composition

11.25

6.55

55.9

33.3

0.127

0.078

Stab detonator (2 discs), type 1

4.16

5.11

37.2

23.5

0.083

0.059

Stab detonator (2 discs), type 2

4.15

5.16

37.2

23.5

0.083

0.054

Stab detonator (1 disc), type 1

4.21

5.44

37.2

23.5

0.083

0.054

Stab detonator (1 disc), type 2

5.69

14.74

45.1

27.4

0.098

0.069

Flash sensitive detonator

4.20

5.44

37.2

23.5

0.083

0.054

IEBW

a

(instantaneous)

7.23

48.75

51.0

32.3

0.113

0.078

IEBW

a

(50 ms delay)

7.20

97.50

51.0

32.3

0.113

0.078

Stab igniter (2 discs), type 1

4.81

4.55

41.2

25.5

0.088

0.059

Stab igniter (2 discs), type 2

5.63

3.87

45.1

27.4

0.098

0.069

a

Instantaneous electric bridgewire detonator

176

R. K. Wharton, A. W. Train, P. F. Nolan, and S. C. Campbell

Propellants, Explosives, Pyrotechnics 26, 174–179 (2001)

The main findings, however, relate to the minimum impact

stimulus required for initiation: the lowest piston velocity to
result in ignition was 0.86 m s

ÿ

1

(equivalent to 0.15 MPa

pressure), while the maximum velocity required was
1.72 m s

ÿ

1

(a pressure of 0.85 MPa).

For the electric cap containing conducting composition, a

maximum gas pressure of 0.9 MPa was used and this did not
produce an ignition.

The data summarized in Table 2 show clear differences in

the response of a range of initiation devices to an impact
stimulus and this could provide useful input to a broader
assessment of the hazards associated with the industrial
handling of such items.

Emphasis is often placed on determining the minimum

ignition stimulus for initiators in terms of the transmitted
energy with a view to comparing this with the maximum
energy likely to be applied accidentally, thus gaining an
estimate of the margin of safety. Unfortunately there is little
knowledge relating to how much energy would actually be
imparted to an initiator during manual handling and hence it
is not possible to base a system of safety margins for the
handling of detonators on minimum ignition energies even
though these data are often available.

Comparison of the all fire energies for drop ball tests

listed in Table 3 with the impact energies in Table 2
indicates that for percussion caps the latter were lower,
whereas for the stab igniters and stab detonators this
situation is reversed. This can be ascribed to the differences
in the tip sizes of the firing pin in the drop ball test and the
firing pin tool in the pneumatic piston apparatus. The firing
pin tool was of similar diameter to the firing pins used in the
drop ball tests on percussion caps but much larger in
diameter than the pins used in drop ball tests with the
stab igniters and detonators.

The minimum impact energies in Table 2 can also be

compared with the maximum compression energies gener-
ated using the firing pin tool in the pivoted beam test.
A typical example is the minimum impact energy of
26.1 mJ for the stab detonator with two discs (red impacted)
compared with the maximum imparted compression of
192 mJ: apart from one isolated case, the trend was for

significantly more energy to be supplied during compression
than during impact. The fact that no ignitions resulted in the
compression tests may indicate that initiation depends not
only on the magnitude of the energy but also on the rate at
which it is applied. Durand and co-workers

(14)

have pre-

viously reached a similar conclusion.

Generally, safety margins can be expressed as the differ-

ence or the ratio of the maximum predicted value of a
quantity and the minimum value of that quantity that will
produce an event. For instance, for the handling of initiators
the ratio of the minimum handling stimulus required to
initiate a device to the maximum stimulus that could be
exerted by a typical person handling the initiator would be a
useful measure of safety. However, since it was not possible
to establish the minimum stimulus required to initiate any of
the devices that were tested, this ratio can be usefully
modified to involve comparison of the maximum handling
stimulus applied to an initiator that does not result in ignition
with the maximum stimulus that could be exerted by a typical
person when handling the initiator.

Although the experimental work was unable to define the

input stimulus in terms of energy, results were available for
both the maximum force applied to an initiator during testing
and the peak rate at which that force was applied. It is
therefore possible to define a compression force safety
margin factor (CFS) as the ratio of the maximum force
applied to an initiator by a test apparatus that does not
produce an ignition to the maximum force that a typical
adult could apply to that initiator. Similarly, a compression
rate safety margin factor (CRS) can be defined as the ratio of
the maximum rate at which a force is applied to an initiator by
a test apparatus that does not produce an ignition to the
maximum rate at which a typical adult could apply that force
to that initiator.

Values of CFS and CRS for both males and females

handling detonators examined in the compression studies
were evaluated for both the pivoted beam and pneumatic
piston apparatus. The results are summarized in Tables 6 and
7, respectively.

Whereas stab detonators appear to have the greatest

margin of safety from the data presented in these tables,

Table 5. Mean Forces and Mean Peak Force Application Rates Produced by the Two Compression Test Apparatuses

Pivoted beam apparatus

Pneumatic piston apparatus

Mean
force
(N)

Mean peak force

application rate (N=ms)

Mean

force

(N)

Mean peak force

application rate (N=ms)

RT

a

FPT

b

KET

c

RT

FPT

KET

13.4

0.39

0.63

0.56

18.4

0.94

0.61

0.56

32.9

0.89

0.97

1.11

33.3

1.29

0.92

0.92

52.5

1.29

1.29

1.41

47.7

1.56

1.24

1.25

69.4

1.95

1.76

1.79

81.7

1.80

1.62

1.64

85.9

1.23

1.11

1.11

141.9

3.15

2.15

2.44

150.6

1.6

1.75

1.70

216.8

4.02

3.05

2.92

213.1

2.22

2.22

2.27

286.8

5.24

3.50

3.56

275.9

2.77

2.78

2.88

a

Rubber-tipped tool

b

Firing pin tool

c

Knife-edge tool

Propellants, Explosives, Pyrotechnics 26, 174–179 (2001)

Hazard in the Manual Handling of Explosives Initiator Devices

177

consideration should also be given to the fact that all the
initiators were subjected to the same compression forces
during testing and that none of the devices were initiated in
the tests. The variations in the values of CFS and CRS can be
largely attributed to the differences in the estimated handling
forces for each initiator as a result of their different sizes.

Bailey and Thomson

(15)

have discussed the essential

factors that need to be considered when developing a
hazard index for energetic materials (including explosives).
In a later study

(16)

, the range of different stimuli, were

assigned different classifications according to whether they
were very sensitive, sensitive or comparatively insensitive.
The results obtained correlated well with documented
records of industrial accidents involving explosives.

Thus the CFS and CRS could be used in assessing the

sensitiveness of initiators to handling forces and form part of
a wider safety-in-handling index.

One of the additional factors that would need to be

incorporated into such an index is an assessment of the
consequences of an initiator exploding in close proximity

to an operator. The effect of blast, but not fragment hazard,
can be roughly ranked by comparing the overpressures
derived from the peak sound pressure levels generated at a
fixed point from the detonators when they are functioned.
Table 8 presents the data derived from such measurements
when ranked relative to the performance of one of the Berdan
type caps. The results indicate that the stab detonators and
igniters are more powerful than the percussion caps.

Although it has not been possible to derive a safety-in-

handling hazard index directly from the present study, data
for certain parameters that are important in assessing the
safe handling of initiators have been obtained, and these
could form an important input to future hazard index
development.

4. Conclusions

It has been shown that the sensitiveness of initiators is

affected by the rate at which energy is transferred to them.

Table 6. Compression Force and Compression Rate Safety Margin Factors Evaluated from Tests with the
Pivoted Beam Apparatus

Initiator type

CFS

CRS

Male

Female

Male

Female

Electric cap, conducting composition

5.1

8.6

41.3

67.2

IEBW, instantaneous

5.6

8.9

46.4

67.2

IEBW, delay

Stab type igniter (two discs), type 1

6.4

10.5

53.5

75.9

Stab detonator (one disc)

Stab type igniter (two discs), type 2

7.0

11.2

59.5

88.8

Berdan cap, type 1

7.7

12.2

59.5

88.8

Stab detonator (two discs), type 1
Stab detonator (two discs), type 2
Stab detonator (one disc)
Flash sensitive detonator

7.7

12.2

63.1

97.0

Table 7. Compression Force and Compression Rate Safety Margin Factors Evaluated from Tests with the
Pneumatic Piston Apparatus

Initiator type

CFS

CRS

Male

Female

Male

Female

Electric cap, conducting composition

4.9

8.3

21.8

35.5

IEBW, instantaneous

5.4

8.5

24.5

35.5

IEBW, delay

Stab type igniter (two discs), type 1
Stab detonator (one disc)

6.1

10.1

28.3

40.1

Stab type igniter (two discs), type 2

6.7

10.8

31.5

46.9

Berdan cap, type 1

7.4

11.7

31.5

46.9

Stab detonator (two discs), type 1
Stab detonator (two discs), type 2
Stab detonator (one disc)
Flash sensitive detonator

7.4

11.7

33.4

51.3

178

R. K. Wharton, A. W. Train, P. F. Nolan, and S. C. Campbell

Propellants, Explosives, Pyrotechnics 26, 174–179 (2001)

However, the study was unable to determine whether or not
the range of initiators examined was actually sensitive to
manual handling forces.

It was not possible to evaluate the quantity of energy

imparted to a detonator on handling, nor could the minimum
impact energies or drop ball energies be used to estimate the
minimum compression energy for initiation. Hence, useful
safety margins based on energy input are unable to be derived
and safety margins are best estimated from either the forces
applied to the initiators or the peak rate at which they were
applied.

Our recent work in this area, which is reviewed in this

paper, has provided data on the handling forces that males
and females can apply to small objects, the sensitiveness of
a range of initiators when exposed to such forces, and an
appreciation of their explosive power. These parameters may
provide a useful input to the development of future safety-in-
handling hazard indexes.

5. References

(1) S. C. Campbell, ‘‘Development of an Apparatus to Help Assess

the Sensitiveness of Explosive Initiating Devices to Manual
Handling Forces’’, Ph.D. thesis, South Bank University, 1999.

(2) S. C. Campbell, P. F. Nolan, R. K. Wharton and A. W. Train,

‘‘Measurement of Forces Exerted in the Manual Handling of
Small Cylindrical Objects’’, Int. J. Indust. Ergon. 25, 349 (2000).

(3) S. C. Campbell, P. F. Nolan, R. K. Wharton and A. W. Train,

‘‘Development of an Apparatus to Assess the Safety in Handling
of Initiating Devices’’, 21st International Pyrotechnics Seminar,
Moscow, 11–15 September 1995, pp. 109.

(4) S. C. Campbell, ‘‘Research to Develop a Method of Assessing

Safety in the Handling of Initiating Devices’’, Explosives Engi-
neering, March 1996, p. 12.

(5) R. K. Wharton, A. W. Train, P. F. Nolan and S. C. Campbell,

‘‘The Development and Application of a Pivoted Beam Test for
Assessing Safety in the Handling of Initiator Devices’’, Pro-
pellants, Explosives, Pyrotechnics 26, 84–90 (2001).

(6) R. K. Wharton, A. W. Train, P. F. Nolan and S. C. Campbell,

‘‘The Development and Application of a Pneumatic Piston Test
for Assessing Safety in the Handling of Initiator Devices’’,
Propellants, Explosives, Pyrotechnics 26, 112–117 (2001).

(7) A. J. Barratt, Health and Safety Laboratory, unpublished results.
(8) Y. Ye, R. Shen and S. Dai, ‘‘Statistical Analysis of Explosive

Accidents’’, 18th International Pyrotechnics Seminar, Breck-
enridge, Colorado, 13–17 July 1992, pp. 1019–1026.

(9) M. Nabiullah, R. N. Gupta and B. Singh, ‘‘Impact Sensitivity and

Thermal Behaviour of Commercial Detonators’’, 15th Interna-
tional Pyrotechnics Seminar, Boulder, Colorado, 9–13 July 1990,
pp. 743–755.

(10) M. Kimura, N. Izawa and M. Goto, ‘‘Impact Sensitivity of

Electric Detonators’’, J. Ind. Explos. Soc. Japan 38, 216 (1977).

(11) K. R. Beaker, ‘‘Input and Thermal Sensitivity of Commercial

Detonators’’, US Bureau of Mines Report RI 8085 (1975).

(12) ‘‘Recommendations on the Transport of Dangerous Goods: Tests

and Criteria’’, 3rd rev. ed., ST=SG=AC.10=11=Rev. 3, United
Nations, New York and Geneva, 1999.

(13) C. M. Woods, M. A. Robinson, C. W. Merten, V. E. Robbins and

D. R. Begeal, ‘‘Instrumented Drop Ball Tester for Percussion
Primers’’, 16th International Pyrotechnics Seminar, Jo¨nko¨ping,
Sweden, 24–26 June 1991, pp. 902–914.

(14) N. A. Durand, R. R. Weinmaster and T. M. Massis, ‘‘Hermetic

G-16 Percussion Primer’’, 13th International Pyrotchnics Semi-
nar, Grand Junction, Colorado, 11–15 July 1988, pp. 197–207.

(15) A. Bailey and B. J. Thomson, ‘‘Is a ‘Hazard Index’ for Explo-

sives and Energetic Materials Achievable?’’, 14th International
Pyrotchnics Seminar, Jersey, Channel Islands, 18–22 September
1989, pp. 347–354.

(16) A. Bailey, D. Chapman, M. R. Williams and R. Wharton, ‘‘The

Handling and Processing of Explosives’’, 18th International
Pyrotechnics Seminar, Breckenridge, Colorado, 13–17 July 1992,
pp. 33–49.

Acknowledgements

The authors would like to thank the safety officers and production

staff of those companies in the UK explosives industry that provided
assistance to the research reported in this paper. South Bank University
staff would like to thank the Health and Safety Executive for financial
support.

(Received October 9, 2000; Ms 2000=044)

Table 8. Relative Explosive Power of the Initiators Using Blast Overpressure Derived from Peak Sound
Pressure Levels

Initiator type

NEQ (mg)

Estimated relative

explosive power

Berdan cap, type 1

16

1.0

Berdan cap, type 2

32

1.4

Boxer cap

22

7.4

Stab type igniter (two discs), type 1

136

10.6

Stab detonator (two discs), type 1
Stab detonator (two discs) type 2

(estimated) 130

25.5

Stab type igniter (two discs), type 2

104

26.3

Stab detonator (one disc), type 1

150

30.2

Flash sensitive detonator

146

36.7

Stab detonator (one disc), type 2
Electric cap, conducting composition

195

(estimated) 193.0

Propellants, Explosives, Pyrotechnics 26, 174–179 (2001)

Hazard in the Manual Handling of Explosives Initiator Devices

179